A Robust Bundled and Wrapped Structure Design of Ultrastable Silicon Anodes for Antiaging Lithium-Ion Batteries

Silicon with its high theoretical specific capacity for Li-ion storage has long suffered from its huge volume expansion and low intrinsic electronic properties, leading to poor rate performance and cycling stability. Recently, considerable efforts have been placed on achieving increased cycle life using nanomaterial structuring approaches. However, finding an efficient strategy to realize high capacity with a long cycle life of Si anodes is still a great challenge. In this work, a novel multileveled design of a web-like morphology is reported as a highly stable 3D interconnected Si network. This heterostructure of nano-sized Si (nSi), nitrogen-doped carbon nanotubes (N-CNTs), and graphenized polyacrylonitrile (g-PAN) is prepared via a low-cost method as an anode for LIBs. This sturdy composite integrates the individual benefits from each of its components, where nSi delivers high energy storage capacity, N-CNTs with nitrogen functionalization act as electron highways and flexible networks to connect nSi particles, and g-PAN produces nitrogen-doped graphene sheets wrapped around the entire electrode structure and buffers the volume change during lithiation. We found that only when all three components are present that significant enhancements in performance are observed. Specifically, this heterostructure exhibits excellent stability with a reversible capacity of ∼1370 mAh g-1 over 1100 cycles at a high current rate of 3000 mA g-1. Moreover, high loading cycling of up to 3 mAh cm-2 at ∼1 mgSi cm-2 was achieved at 500 mA g-1. This effective strategy introduces a promising avenue for the scalable production of high-performance next-generation LIBs.